Dual pump system

ABSTRACT

A dual pump system having a housing with a fluid inlet and a fluid outlet and two working chambers with pump members respectively disposed therein. A fluid passageway extends in the housing between the chambers, and a check valve is disposed in the passageway for preventing flow from the high pressure chamber to the low pressure chamber. There is a pressure relief port in fluid flow communication with the low pressure chamber, and there is a valve seat and a valve closure adjacent the port for controlling flow through the port, and there is a spring acting against the valve closure to hold it on the seat up to a limit of force of the fluid pressure. A push rod extends from the high pressure chamber and to the valve closure to hold the valve closure off its seat, under the influence of pressure in the high pressure chamber.

United States Patent [1 1 Hahn I [5 DUAL PUMP SYSTEM [75] Inventor:

[7 3] Assignee: Hahn Hydraulics lnc., Racine, Wis.

22 Filed: Apr. 9, 1973 [21] Appl. No.: 348,975

Rea I. Hahn, Racine, Wis.

[ Apr. 23, 1974 Primary Examiner-William L. Freeh Assistant Examiner-Gregory Paul LaPointe Attorney, Agent, or Firm-Arthur J. Hansmann [5 7] ABSTRACT A dual pump system having a housing with a fluid inlet and a fluid outlet and two working chambers with pump members respectively disposed therein. A fluid passageway extends in the housing between the chambers, and a check valve is disposed in the passageway for preventing flow from the high pressure chamber to the low pressure chamber. There is a pressure relief port in fluid flow communication with the low pressure chamber, and there is a valve seat and a valve closure adjacent the port for controlling flow through the port, and there is a spring acting against the valve closure to hold it on the'seat up to a limit of force of the fluid pressure. A push rod extends from the high pressure chamber and to the valve closure to hold the valve closure off its seat, under the influence of pressure in the high pressure chamber.

7 8 Claims 4 Drawing Figures 1 I DUAL PUMP SYSTEM This invention relates to a dual pump system, and, more particularly, it relates to a hydraulic type of pump which has a low pressure chamber and a high pressure chamber, and valve means are employed for controlling the flow of fluid between and from the chambers.

BACKGROUND OF THE INVENTION Dual pump systems, of the hydraulic fluid or other type of fluid, are already commonly known in the art. These pumps operate to receive fluid at the inlet to the low pressure side of the'pump and to raise the fluid pressure and pass the fluid to the high pressure side of the pump where the fluid pressure is further raised and finally exhausted from the pump at the higher pressure. In this arrangement, it is common to have the low pressure pump act as a large volume pump so that the output from the low prcssurelpu'mp can cause a large action or stroke or movement in the output force from the low pressure side of the pump. Similarly, the high pressure pumpthen creates a relatively smaller moving force but at a higher magnitude of force so that a greater pressure or the higher force can be created through the smaller stroke or movement. This type of action is desirable in the example of where the initial 7 work forceis creating a large stroke or movement, and

then the final force is at a higher magnitude but isof a smaller stroke or movement. For instance, in a trash pump system is shown in S.Pat. No. 2,957,419 where a relief valve is utilized between two pump units;

and a similar disclosure is shown in US. Pat. No.

However, in the prior art dual pump systems, the

structures are complex. and commonly are arranged and require that fluid lines and checkvalves extend exteriorly of the pjump-housin'g'itself, for governing and controlling the fluid pressure between the stages of the pumping action. Such shortcomings are shown in the patents referred to above, In the present invention, the dual pump system is provided with integral passageways and valves and control pieces which are all within the housing and are therefore compact and most efficient, and no problems of fluid leakage exist, and no external connections or parts are required. Accordingly, it is the general object of this invention to improve the pose of maintaining the operation of the low pressure pump of the pump system when the high pressure pump is in operation, and this objective is achieved in the compact and efficient and readily and easily provided 7 pressure and low pressure pumps of the pump system are the same or single outlet, and the outlet of the low pressure pump and the high pressure pump both direct vthe fluid to the single outlet of the pump system housing.

A more specific object of this invention is to provide a dual pump system wherein the pressure in the outlet of the low pressure pump can be relieved when the lower pressure pump of the pump system has achieved that pressure, and a valve is then opened to relieve the pressure in the outlet of the low pressure pump, and the valve is maintained open under the influence of the pressure in the outlet of the high pressure pump, and a check valve is employed for preventing return flow from the high pressure pump to the low pressurepunip, and thereby the pump can be operated at the high pressure condition but without requiring significant power for'operatingthe low pressure portion'ofthe'pump at the time that the high pressure is being produced.

Other objects and advantages willbecome apparent uponreadingthe following description in light of the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS.

FIG. 1 ,is atop plan view of a pump incorporating a preferred embodiment of this invention.

FIG. 2 is. a sectional view taken on the line 2-2 of FIG. 1. p b

FIG. '3 is a sectional view taken on the line 3-3 of FIG. 1.

structure and function of the dual pump systems herehas been reached, all for providing a compact, efficient, and low power consumption pump which utilizes the maximum of its power input forpi'oducing the pressure and flow of the pump output. That is, the pump system is not required to consume power for the pur- FIG. 4 is a sectional view 'taken on the line 4-4 of FIG. 1.

DETAILED DESCRIPTION OF THE. PREFERRED EMBODIMENT The drawings show a pump housing 10 existing in a low pressure end piece 11, a center housing piece 12,

I and a high pressureend piece 13.. A low pressure pump ring piece and a high.pressure pump'ring piece 16 are sandwiched in with the other housing pieces 1 1, l2

and 13, and all five pieces are held in axial alignment by the housing screws 17 extending through the pieces; A fluid inlet connector 18 and a fluid outlet connector 19 are attached at opposite axial ends of the housing 10 for directing fluid to and from the housing, respectively. A shaft 2 1 extends from the housing 10 and is available for connecting a drive mechanism to the shaft 21 to rotate the latter and thereby rotate the pumping gears which are within the housing 10 andwhich are shown in FIG. 2 to be the low pressure pumping gears 22, and which'are shown in FIG. 3' to be the high pressure pumping gears 23. Therefore, two sets of gears or pump members 22 and 23 are provided, and they are located as indicated in FIGS. 1, 2 and 3, and they are under the influence of the rotation of the drive shaft 21 so that the gears 22 rotate in the direction of the arrows designated A, and the gears 23 rotate in the'direction housing and supports one of the gears 22 and one of the gears 23, in a usual manner and as shown in F 16$. 2 and 3.

. Therefore, fluid, such as a hydraulic oil, enters the pump inlet connection 18 and flows through the pump inlet passageway 26 to enter the low pressure pump suction chamber designated 27 and this chamber is within'the low pressure housing ring 14, as shown. Fluid is pumped from the suction chamber 27 and to a low pressure chamber and to a passageway 28 which extends between the low pressure chamber 25 and the outlet connector 19 in the housing piece 12. The high pressure stage has a suction chamber 29 and there is a fluid passageway 31 which extends through thepiece 12 and between the chambers 27 and 29 for flow to the respective chambers on the fluid inlet sides of the chambers relative to the gears 22 and 23. Also, there is a high pressure chamber connected with the outlet connector 19. With this arrangement, fluid is introduced into each of the working chambers 27 and 29, and each set of gears 22 and 23 pumps and pressurizes the fluid to the outlet 19, with the gears '22 being a high volume but low pressure type pump and the gears 23 being a low volume but high pressure type pump, and the output from .both chambers 25 and 30 being directed to the housing outlet passageway 32, as seen in FIG. 4, and the passageway 32 connects with the outlet connector 19.

FIG. 4 further shows a check valve-33 disposed between'the chambers 25 and 30 and being slidable on a push rod 34 which extends from the high pressure chamber 30 and through the low pressure chamber 25 and to a ball closure 36. Thus, the check valve 33 is shown to have a tapered end 35 which fluid-tightly seats on a seat 38 extending around the passageway 28, as shown. The check valve 33 permits fluid to flow from the low pressurechamber 25 and to the outlet 32 until the high pressure chamber 30 presents its pressure to the check valve 33 and causes it to move to the right, from the position shown in FIG. 4, and to thus seat on the seat 38 and prevent flow between the chambers 25 and 30. It will also be understood that the check valve 33 is piloted on the rod 34 and slides thereon, as described. Further, when high pressure is developed in the chamber 30, due to the rotation of the high pressure gears 23, then the rod 34 is shifted to the right, as seen in FIG. 4, under the influence of high pressure, and the rod 34 then bears against the ball closure 36. Still further, it will be seen that the ball closure 36 fluidtightly seats on a port 37 which is in flow communication with the low pressure chamber 25 through a passageway 40.

The ball closure 36 is yieldingly held on the seat 37 by a spring 39 which extends through a tubular piece 41 affixed to the housing 10. A back-up and adjustable plug 42 adjustably holds the spring 39 in the piece 41 so that variable pressure can be applied to the spring 39 and thus against the ball closure 36. The force applied by the resilient member 39 is set to co-ordinate with the force created by the pressure in the chamber 25 as ap plied against the ball closure 36. That is, when the fluid pressure in the chamber 25 reaches a selected magnitude, the ball closure 36 is unseated and the pressure developed in the chamber 25 is relieved, rather than being directed to the passageway 28 and the outlet 32, and such relief is created by the flow of the low pres sure fluid through the passageway and past the ball closure 36, and it can go to an outlet 43 in the piece 41 which is a fluid-flow line. Also, when the selected low pressure is reached asrnentioned, then the check valve 33 is seated and the high pressure fluid in the chamber 30 applies against the push rod 34 to displace the rod 34 to the right, as viewed in FIG. 4, and this holds the closure 36 off its seat, and thus only a little, if any, power is required in the operation of the low pressure gear members 22, even though they are on the shafts 21 and 24, which are the common shafts for both sets of gears 22 and 23. Still further, the push rod 34 has an enlarged end 44 which bears against the check valve 33 to further seal the flow of any fluid from the high pressure chamber 30 and past the check valve 33.

. The drawings further show that a sleeve piece 46 is fixedly mounted in the housing and presents the passageway 28 and contains the check valve 33 and the one end of the push rod 34, as shown. Also, the piece 46 has a pin 47 whichserves as a stop for the push rod 34 and prevents it from moving to the left, from the position shown in FIG. 4. Y

With the embodiment described, there is provided the dual pump system having the low pressure high volume pump portion in ring 14 and the high pressure low volume pump portion in ring 16, and having the check valve 33 and the relief valve with the closure 36 and the seat 37, and with the relief valve being under the. influence of the spring 39 which is adjustable through the threaded member 42 in the piece 41. In operation, both pumps initially pump to the outlet 32. When low pressure is reached, closure 36 is opened, and the low pressure pump output is dumped, valve 33 is closed, and the high pressure pump holds the closure 36 off seat 37 as only the high pressure pump continues to pump to the outlet 32. Both the check valve 33 and the push rod 34 are under the influence of the high pressure chamber 30, and thus the chambers can be fluid-tightly separated, and the relief valve closure 36 can be maintained off its seat with only an insignificant amount of power consumed, and the low pressure pump side need not be operating to simply turn or consume power when only the output of the high pressure pump is desired. It will of course be seen and understood that the check valve 33 has its conical end 35 available for fluid-tightly seating with the conical seat 38, and, similarly, the push rod end 44 has a conical end 48 which-seats against the end of the check valve 33 under the pressure of the fluid in the high pressure chamber 30, for snug seating in both instances.

By way of further example, one application of this dual pump system is in connection with a trash compactor where the output fluid is used for driving the working member or piston of the Compactor. In that instance, the major portion of the piston stroke is with only a minimum of force required but, being a large stroke, the low pressure but high volume pump provides adequate stroke or power. However, at the end of the stroke, of perhaps the last one fifth of its length, the output of the high pressure pump is utilized for rendering the greater force to the piston, though it is then only a shorter stroke. With this arrangement, the piston stroke can be accomplished, as described, but only a minimum of power is required for operating the system.

What is claimed is: 1. In a dual pump system of the type including a housing. having a fluid inlet and a fluid outlet and, relative to each other, a low pressure and a high pressure working chamber, with both of said chambers being in fluid flow communication with each other and with said inlet and said outlet, pump members rotatably disposed in each of said chambers, with said chambers respectively being low-pressure large volume and high-pressure small volume pump members, relative to each other, a drive shaft connected with said members and extending from said housing for rotating said members to create said fluid pressures, a relief valve operatively connected with said lowpressure chamber for relieving fluid pressure at a limit of pressure, the improvement comprising said housing having a fluid passageway extending in said housing and between said chambers for the flow of fluid from said low pressure chamber to said high pressure chamber, a check valve disposed in said fluid passageway for preventing the flow of fluid from said high pressure chamber to said low pressure chamber, a pressure relief fluid-flow port in fluid-flow communication with said low pressure chamber, a valve seat and a valve closure disposed adjacent said pressure relief fluid-flow port and with said valve closure acting on said port, a force-yielding member operatively associated with said valve closure for holding the latter on its said seat and against the force of the fluid pressure in said low pressure chamber and up to a limit of magnitude of force, and a member extending from said check valve to said valve closure and being movable in response to fluid pressure in said high pressure chamber to hold said valve closure off its said seat.

2. The dual pump system as claimed in claim 1, wherein said check valve is disposed on said member for closing off fluid pressure from said high pressure chamber to the end of said member toward said valve closure and with the other end of said member being exposed to the fluid in said high pressure chamber for the movement of said member to hold said valve closure off its said seat.

3. The dual pump system as claimed in claim 1, wherein said member extends through said passageway to extend from said high pressure chamber to said valve closure.

4. The dual pump system as claimed in claim 1, in-

cluding a fluid-flow line connected with said housing at said port and extending therefrom for guiding the flow of the fluid from said port.

5. The dual pump system as claimed in claim 1, wherein said member is a push rod extending through said passageway to extend from said high pressure chamber to said valve closure, an annular seat disposed between said chambers and surrounding said passageway and faced toward said high pressure chamber, and said check valve being'a sleeve slidably disposed on said push rod for movement onto and off said annular seat.

6. The dual pump system as claimed in claim 1, including a valve closure and seat combination on said member and said check valve, and with said combination being disposed for seating engagement when said member is moved toward said valve closure.

7. The dual pump system as claimed in claim 1, wherein said check valve is exposed to the fluid pressure of said high pressure chamber and is movable independent of the position of said member, for closing off fluid flow between said chambers, and said member being exposed to the fluid pressure of said high pressure chamber, for closure-holding-movement only after said check valve is seated, and said check valve and said member having a valve seat and closure combina- .tion for full and final fluid sealing of flow from said high pressure chamber to said low pressure chamber.

8. The dual pump system as claimed in claim 1, wherein said member is a push ro-d extending through said passageway to extend from said high pressure chamber to said valve closure, an annular seat disposed between said chambers and surrounding said passageway and faced toward said high pressure chamber, and said check valve being a sleeve slidably disposed on said push rod for movement onto and off said annular seat, and including a valve closure and seat combination on said push rod and said check valve, and with said combination being disposed for seating engagemerit when said member is moved toward said valve closure. 

1. In a dual pump system of the type including a housing having a fluid inlet and a fluid outlet and, relative to each other, a low pressure and a high pressure working chamber, with both of said chambers being in fluid flow communication with each other and with said inlet and said outlet, pump members rotatably disposed in each of said chambers, with said chambers respectively being low-pressure large-volume and high-pressure small volume pump members, relative to each other, a drive shaft connected with said members and extending from said housing for rotating said members to create said fluid pressures, a relief valve operatively connected with said low-pressure chamber for relieving fluid pressure at a limit of pressure, the improvement comprising said housing having a fluid passageway extending in said housing and between said chambers for the flow of fluid from said low pressure chamber to said high pressure chamber, a check valve disposed in said fluid passageway for preventing the flow of fluid from said high pressure chamber to said low pressure chamber, a pressure relief fluid-flow port in fluid-flow communication with said low pressure chamber, a valve seat and a valve closure disposed adjacent said pressure relief fluid-flow poRt and with said valve closure acting on said port, a forceyielding member operatively associated with said valve closure for holding the latter on its said seat and against the force of the fluid pressure in said low pressure chamber and up to a limit of magnitude of force, and a member extending from said check valve to said valve closure and being movable in response to fluid pressure in said high pressure chamber to hold said valve closure off its said seat.
 2. The dual pump system as claimed in claim 1, wherein said check valve is disposed on said member for closing off fluid pressure from said high pressure chamber to the end of said member toward said valve closure and with the other end of said member being exposed to the fluid in said high pressure chamber for the movement of said member to hold said valve closure off its said seat.
 3. The dual pump system as claimed in claim 1, wherein said member extends through said passageway to extend from said high pressure chamber to said valve closure.
 4. The dual pump system as claimed in claim 1, including a fluid-flow line connected with said housing at said port and extending therefrom for guiding the flow of the fluid from said port.
 5. The dual pump system as claimed in claim 1, wherein said member is a push rod extending through said passageway to extend from said high pressure chamber to said valve closure, an annular seat disposed between said chambers and surrounding said passageway and faced toward said high pressure chamber, and said check valve being a sleeve slidably disposed on said push rod for movement onto and off said annular seat.
 6. The dual pump system as claimed in claim 1, including a valve closure and seat combination on said member and said check valve, and with said combination being disposed for seating engagement when said member is moved toward said valve closure.
 7. The dual pump system as claimed in claim 1, wherein said check valve is exposed to the fluid pressure of said high pressure chamber and is movable independent of the position of said member, for closing off fluid flow between said chambers, and said member being exposed to the fluid pressure of said high pressure chamber, for closure-holding movement only after said check valve is seated, and said check valve and said member having a valve seat and closure combination for full and final fluid sealing of flow from said high pressure chamber to said low pressure chamber.
 8. The dual pump system as claimed in claim 1, wherein said member is a push rod extending through said passageway to extend from said high pressure chamber to said valve closure, an annular seat disposed between said chambers and surrounding said passageway and faced toward said high pressure chamber, and said check valve being a sleeve slidably disposed on said push rod for movement onto and off said annular seat, and including a valve closure and seat combination on said push rod and said check valve, and with said combination being disposed for seating engagement when said member is moved toward said valve closure. 